Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/10—Organic polymers or oligomers
  • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
  • H10K85/113—Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
  • H10K85/1135—Polyethylene dioxythiophene [PEDOT]; Derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/06—Luminescent materials, e.g. electroluminescent or chemiluminescent containing organic luminescent materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/30—Coordination compounds
  • H10K85/321—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3]
  • H10K85/324—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3] comprising aluminium, e.g. Alq3
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/60—Organic compounds having low molecular weight
  • H10K85/631—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine

Definitions

• the invention relates to electroluminescent arrangements which contain conductive polymers, especially 3,4-polyalkylenedioxythiophenes, as auxiliary layers, and to 3,4-polyalkylenedioxythiophene dispersions.
• An electroluminescent (EL) arrangement is characterized in that it emits light on application of an electric voltage with flow of a current.
• LEDs light emitting diodes
• the emission of light occurs through positive charges (holes) and negative charges (electrons) recombining with emission of light.
• organic EL arrangements generally contain one or more layers of organic charge-transport compounds.
• the principal layer structure is as follows:
• an EL arrangement consists of two electrodes between which is located an organic layer, which takes on all functions—including that of emission of light.
• Systems of this type are described, for example, in WO 90/13148 on the basis of poly[p-phenylene-vinylene].
• At least one of the current-carrying electrodes 2 or 8 must consist of a transparent and conductive material.
• Suitable as substrate 1 are transparent supports, such as glass or plastic films (for example polyesters, such as polyethylene terephthalate or polyethylene naphthalate, polycarbonate, polyacrylate, polysulfone or polyimide film).
• transparent supports such as glass or plastic films (for example polyesters, such as polyethylene terephthalate or polyethylene naphthalate, polycarbonate, polyacrylate, polysulfone or polyimide film).
• Suitable transparent and conductive electrode materials are:
• metal oxides for example indium tin oxide (ITO), tin oxide (NESA), etc.
• Suitable emitter layers 5 are described, for example, in DE-A 196 27 071.
• EP-A 686 662 discloses the use of specific mixtures of conductive organic polymeric conductors, such as 3,4-polyethylenedioxythiophene and polyhydroxyl compounds or lactams, as electrode 2 in electroluminescent displays.
• conductive organic polymeric conductors such as 3,4-polyethylenedioxythiophene and polyhydroxyl compounds or lactams
• these electrodes do not have adequate conductivity, particularly for large-area displays.
• the conductivity is sufficient for small displays (pixel size ⁇ 1 mm 2 ).
• DE-A 196 27 071 discloses the use of polymeric organic conductors, for example 3,4-polyethylenedioxythiophene, as hole-injecting layers. These enable the luminosity of the electroluminescent displays to be significantly increased compared with superstructures without the use of polymeric organic interlayers. However, the service life of these displays is still not adequate for practical applications.
• EP-A 991 303 discloses 3,4-polyalkylenedioxythiophenes having particle sizes of ⁇ 250 nm and conductivities of the dried polymers of ⁇ 2 S/cm, corresponding to a resistivity of 0.5 ⁇ cm.
• these 3,4-polyalkylenedioxythiophenes are still too conductive.
• the high conductivity results in so-called cross talk between adjacent conductor tracks (see, for example, D. Braun in Synth. Metals, 92 (1998) 107-113).
• the invention relates to a dispersion comprising polyanions and cationic 3,4-polyalkylenedioxythiophenes, wherein at least about 90% of the particles of the dispersion are less than about 50 nm.
• the invention also relates to an electroluminescent arrangement containing a hole-injecting layer, wherein the hole-injecting layer has been produced from a dispersion according to the invention.
• the invention therefore relates to 3,4-polyalkylenedioxythiophene dispersions in which at least about 90% of the particles are less than about 50 nm and the resistivity of coatings produced therefrom is preferably more than about 5000 ⁇ cm. Preference is given to dispersions in which at least about 90% of the particles are less than about 40 nm.
• the invention furthermore relates to electroluminescent arrangements which contain a hole-injecting layer produced from a dispersion according to the invention.
• the particle size was determined in the swollen state by means of an ultracentrifuge. The general procedure is described in Colloid Polym. Sci. 267, 1113 to 1116 (1989). These dispersions were prepared starting from dispersions in accordance with EP-A 991 303 by subsequent comminution of the particles.
• Suitable comminution methods are, for example, grinding by means of ball mills or stirred mills, high-speed stirring, ultrasound treatment and high-pressure homogenization.
• the diameter of the nozzles is between about 1 and about 0.1 mm or, in the case of slot nozzles, the width is from about 0.1 to about 1 mm.
• the homogenization is carried out at pressures of from about 1 to about 2000 bar, preferably from about 100 to about 1000 bar.
• the dispersions according to the invention preferably comprise polyanions and cationic, soluble or insoluble 3,4-polyalkylenedioxythiophenes of the formula I
• the 3,4-polyalkylenedioxythiophene dispersions according to the invention are preferably filtered through a filter before the coating operation.
• polyanions of polystyrenesulfonic acid which can be prepared analogously to EP-A 440 957
• readily filterable dispersions are obtained if from about 6 to about 30 parts by weight of polyanion, preferably from about 8 to about 25 parts of polyanion, based on one part by weight of 3,4-polyalkylenedioxythiophene of the formula I, are used.
• the weight ratio of polycation to polyanion is thus preferably between about 1:8 and about 1:25.
• This ratio of 3,4-polyalkylenedioxythiophene to polyanion can be set directly during the preparation. However, it has been found that it is also possible to start from a solution or dispersion having a higher content of 3,4-polyalkylenedioxythiophene and subsequently to set the ratio according to the invention of 3,4-polyalkylenedioxythiophene to polyanion by addition of polyanions.
• the solids contents of the dispersions according to the invention are between about 0.01 and about 20% by weight, preferably between about 0.2 and about 5% by weight.
• the viscosity of the dispersions at 20° C. is between the viscosity of pure water or the solvent mixture and 200 mPas, preferably less than about 100 mPas.
• the desired amount of water can be removed from the aqueous dispersions by distillation, preferably under reduced pressure, or by another method, for example ultrafiltration.
• Electroluminescent arrangements according to the invention contain a hole-injecting layer produced from a dispersion according to the invention.
• the hole-injecting layer ( 3 ) is produced by known technologies. To this end, a dispersion according to the invention is distributed in the form of a film on a base electrode.
• the solvent used is preferably water or water/alcohol mixtures. Examples of suitable alcohols are methanol, ethanol, propanol, isopropanol and butanol.
• organic, polymeric binders and/or organic, low-molecular-weight crosslinking agents can be added to the dispersions according to the invention.
• Corresponding binders are described, for example, in EP-A 564 911.
• the dispersions of the present invention preferably comprise only small amounts of ionic impurities in the limits as described in EP-A 991 303.
• the dispersion according to the invention can be uniformly distributed on the substrate, for example by techniques such as spin coating, casting, knife coating, printing, curtain coating, etc.
• the layers can subsequently be dried at room temperature or temperatures up to 300° C., preferably from 100 to 200° C.
• the conductivity of the hole-injecting layer ( 3 ) is determined by measuring the surface resistance of the layer.
• the following experimental set-up has proven particularly suitable for this purpose: the hole-injecting layer is coated in a layer thickness d of, for example, 200 nm onto an electrically insulating support, for example a glass substrate, and subsequently carefully dried at from 100 to 300° C. Metal strips are then vapor-deposited onto the layer as electrodes. Highly suitable are gold electrodes vapor-deposited as parallel strips in a vapor-deposition apparatus at a pressure of about 10 ⁇ 6 mbar with the aid of a mask. The strips have, for example, a length l of 20 mm, a width b of 3 mm and a separation a of 1.0 mm.
• the electrical resistance R of the layer is measured between two adjacent electrodes using either the two-pole or the four-pole method. In order to exclude the effect of atmospheric moisture, the resistance measurement is carried out in a dry atmosphere or in a vacuum.
• the measurement set-up can also be achieved by means of ITO electrodes.
• the ITO layer is structured on glass, for example as parallel strips, and the hole-injecting layer is subsequently coated on. The resistance between adjacent ITO electrodes is then measured as described above.
• the dispersion according to the invention may in addition preferably be applied in a structured manner by techniques such as ink jet printing.
• This technique using water-soluble polythiophenes, such as 3,4-polyethylenedioxythiophene, is described, for example, in Science, Vol. 279, 1135, 1998, and DE-A 198 41 804.
• the thickness of the hole-injecting layer ( 3 ) is from about 3 to about 500 nm, preferably from about 10 to about 200 nm.
• the further layers are subsequently applied to the hole-injecting layer ( 3 ) from solution or by vapor deposition.
• the emitter layer 5 used here preferably comprises poly-para-phenylenevinylene derivatives and/or polyfluorene derivatives without an additional hole-transporting layer 4 , or aluminium complexes, such as aluminium quinolate, in combination with a hole-transporting interlayer 4 .
• the function of the hole-injecting interlayer can be tested in a special set-up (see also Synth. Met. 111 (2000) 139).
• the hole-injecting interlayer is applied by means of a spin coater to an ITO substrate that has been cleaned by wet-chemical methods.
• the layer is subsequently heated at 120° C. for 5 minutes.
• the layer thickness is 60 nm.
• Aluminium quinolate (Alq) is applied in the form of a layer with a thickness of 60 nm by vapor deposition as emitter layer.
• An alloy of Mg and Ag is subsequently applied as cathode by vapor deposition.
• the organic light emitting diodes produced in accordance with the invention are distinguished by a long service life, high luminosity, low operational voltages and a high rectification ratio.
• Example 2 of EP-A 991 303 states
• the ion-exchange resins were removed by filtration through a poly-acrylonitrile fabric having a pore size of 50 ⁇ m. A dispersion was obtained having a solids content of about 1.1% by weight that was ready to use. The dispersion could easily be filtered through a 0.22 ⁇ m filter. The filtered dispersion was used for producing electroluminescent displays.
• Coatings were subsequently applied to glass plates by spin coating and dried at 120° C., and the resistivity of the layers was determined under reduced pressure at about 10 ⁇ 6 mbar.
• this hole-injecting interlayer A in organic light emitting diodes was subsequently tested in a set-up consisting of the following multilayer stack: ITO//layer A (60 nm)//TDAPB(100 nm)//Alq(60 nm)//MgAg.
• Coatings were subsequently produced on glass plates by spin coating and dried at 120° C., and the resistivity of the layers was determined under reduced pressure at about 10 ⁇ 6 mbar.
• this hole-injecting interlayer B in organic light emitting diodes was subsequently tested in a set-up consisting of the following multilayer stack: ITO//layer B (60 nm)//TDAPB(100 nm)//Alq(60 nm)//MgAg.
• Coatings were subsequently produced on glass plates by spin coating and dried at 120° C., and the resistivity of the layers was determined under reduced pressure at about 10 ⁇ 6 mbar.
• ITO//layer C (60 nm)//TDAPB(100 nm)//Alq(60 nm)//MgAg.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Electroluminescent Light Sources (AREA)
• Luminescent Compositions (AREA)
• Illuminated Signs And Luminous Advertising (AREA)
• Polyoxymethylene Polymers And Polymers With Carbon-To-Carbon Bonds (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)

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Citations (21)

• 2001
  • 2001-01-26 DE DE10103416A patent/DE10103416A1/de not_active Withdrawn
• 2002
  • 2002-01-14 AT AT02000231T patent/ATE419653T1/de active
  • 2002-01-14 ES ES02000231T patent/ES2319736T3/es not_active Expired - Lifetime
  • 2002-01-14 EP EP02000231A patent/EP1227529B1/de not_active Expired - Lifetime
  • 2002-01-14 PT PT02000231T patent/PT1227529E/pt unknown
  • 2002-01-14 DE DE50213155T patent/DE50213155D1/de not_active Expired - Lifetime
  • 2002-01-14 DK DK02000231T patent/DK1227529T3/da active
  • 2002-01-22 JP JP2002012647A patent/JP4328486B2/ja not_active Expired - Lifetime
  • 2002-01-24 US US10/057,027 patent/US7923475B2/en not_active Expired - Fee Related
  • 2002-01-25 KR KR1020020004450A patent/KR100862402B1/ko not_active Expired - Lifetime
  • 2002-01-25 TW TW091101199A patent/TW595029B/zh not_active IP Right Cessation
• 2009
  • 2009-03-31 CY CY20091100376T patent/CY1108948T1/el unknown

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